Tori Tomlin, Newcastle, writes In October I collected a hire car from National Car on the Greek island of Cephalonia to drive to our villa just outside Fiskardo. As we drove along the main highway a large rock fell into the road right in front of the car and I was forced to drive over it.

The rock damaged the power steering but we were able to continue driving to the villa. I reported the incident to National, which sent us another vehicle.

When we returned the replacement car two weeks later, National presented us with a document claiming that the repairs would cost €2,225 (£1,890). Apparently, we were uninsured for this incident because the underside of rental cars is not covered by collision-damage- waiver insurance (CDW).

The terms and conditions printed on the back of the rental contract say, however, only that there is no cover for “damage to the underside of the automobile whilst [it is] being driven on the edge of the road (gutter) or on unsealed roads”.

I feel that because this happened on a main road I should have to pay only the CDW excess for the damage, which is €865 (£734). However, a total of €2,255.83 (£1,915) has been deducted from my credit card – €30 more than the quotation I was given.

The situation has been complicated by the fact that I used Auto Europe, an online agent, to book the car. Initially I challenged Auto Europe, but it says that its terms and conditions of rental also state that damage to the underside of the vehicle is not covered.

A lot of money has been taken from my account as a result of damage that was no fault of mine. I would really like you to find out why I am liable for this act of God.

Gill Charlton, consumer expert, replies I contacted Auto Europe’s US-based head office, which has taken up your case with National Car at the highest level. I argued that this was an accident, an unavoidable collision with a rock and not negligent damage to the underside occasioned by driving the car off-road.

After a full investigation, Auto Europe says that you simply have no cover for this type of incident – whatever the circumstances. On your signed rental agreement it does clearly state: “No insurance covers tyres, mirrors, glasses, the inside and the underpart of the car”. This information is also repeated on the Auto Europe voucher.

These exclusions are standard practice in the car rental industry. Most companies provide top-up insurance both to reduce the CDW excess to zero and cover these excluded damages. However, National in Greece does not provide such cover.

Auto Europe did offer you the option of paying for a “refundable excess” when you made the reservation. Adding this refundable excess option – where the broker refunds any damage charges billed by the supplier – would have added £50 to your rental cost. The chief executive of Auto Europe has confirmed that if you had purchased this option he would have agreed to refund the damage to the underside of your car.

As your experience shows, the total exclusion of insurance cover for any damage to any element of the underside of a vehicle is a gaping hole in holiday car insurance. One way to avoid being caught is to buy an annual top-up policy from a specialist broker. Insurance4carhire (0844 892 1770; insurance4carhire.com) offers £5,000 of cover for £49.99 a year. This includes covering the CDW and theft excess as well as damage to windows, roof, undercarriage and tyres.

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About Gill Charlton

Gill is an expert on Cornwall and consumer issues, especially legal disputes.